Im curious, what do you use/recommend for monitoring and tracing?
When without a GUI I use the built-in dbg module. Sometimes via the recon_trace wrapper to get the tracing to be rate limited (if on a production cluster).
ttb built-in modules used for tracing on multiple nodes, capture more data and then save to a file and inspect later.
eflame or eep (not the Erlang Proposal, the profiling tool) + kcachegrind to view results.